This invention relates in general to measuring and marking devices of the type used in building frame construction. Specifically, this invention relates to a bolt hole marker used for marking the location of bolt holes in the base plate of frame construction utilizing concrete slab floors.
A conventional technique used in construction of residential and commercial buildings involves concrete foundations made of poured concrete with threaded securing bolts being set upright in the edges of the wet concrete for subsequently securing the base plate, also called a mudsill, in the frame structure. In the past, the wood mudsill was marked for the drilling of holes to fit over the preset bolts by placing the mudsill on top of the bolts and hitting the wood mudsill with a hammer to leave the impression of the bolt ends on the under side of the mudsill. The problem with this approach was that the bolt portions extending from the concrete floor were sometimes less than perfectly perpendicular, which resulted in the bolt hole marking technique failing to properly align the hole with the actual point of entry of the bolt into the concrete foundation. As a result, the poor alignment of the bolt holes in the mudsill with the actual bolt portions extending from the concrete floor caused the carpenter to expend additional time and effort in straightening the bolts and hammering the mudsill into position. Often times, the mudsill would be split or a bolt would be broken out of the foundation in an attempt to secure the mudsill to the floor.
In an attempt to correct the problem of alignment, workers would, on occasion, drill holes in the wooden mudsill or plate which were larger than the bolt diameters. The problem with this approach was that it lessened the mudsill stability and strength, causing problems in supporting the frame structure erected above the floor.
U.S. Pat. No. 3,406,460, issued Oct. 22, 1968, entitled "BOLT HOLE MARKER" shows a device used to provide improved bolt hold marking for use in frame construction on top of concrete foundations. The device included a handle with a shank extending therefrom, the shank having a centering notch at the end thereof for contacting a bolt. The device also included a fixed punch located on the shank which was centered over the base plate to be marked and which was struck with a hammer to mark the bolt hole position. The punch was not adjustable with respect to the centering notch and no means was provided for aligning the device with respect to the plate edge so that the shank would extend perpendicular to the plate longitudinal axis.